314 



ANATOMY OF THE CENTHAL NERVOUS SYSTEM. 



The Substantia nigra, and witli it the stratum intermedium, do not ap- 

 pear in sections in the region of the pons. Of the continuation of the striae 

 medullares thalami nothing is known with certainty. 



Even before the pontal region begins, the red nucleus always becomes 

 smaller, and the anterior cerebellar peduncle, which arises from it, passes 

 farther and farther to the outside, and finally appears as two strong bundles 

 •of fibers which lie between the region of the red nucleus and the fillet. In 

 Fig. 201a the fundament of the cerebellar peduncle appears; in sections 

 which, falling slightly posterior to this, cut the velum, the peduncles lie 



Fig. 202. — Section through the upper pontal region just posterior to the 

 corpora quadrigemina. From a ninth-month fetus. Biiidcarm, Anterior cere- 

 bellar peduncle. Byiiclcr, Pons. >Sc)ileifc, Fillet. Hint. Liiiigsbundel, Post. long, 

 faseie. 



much nearer to the periphery (Fig. 2016); and in Fig. 202 they form, 

 through the velum medullare posticum, the outer boundary of the figure. 

 Soon afterward they sink into the cerebellum (Fig. 210, R). 



The region which is left free through the disappearance of the red 

 nucleus is appropriated by the now increasing fibers of the substantia reticu- 

 laris, which will be studied later. These are fibers, mostly longitudinal, 

 which may be followed from the lowest levels of the oblongata in gradually 



